Liquid Crystal Composition Vertical Dielectric Constant Contrast
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Solution Overview
Problem
Existing liquid crystal display devices face challenges in achieving high contrast and transmittance due to limited adjustment range of dielectric anisotropy and optical anisotropy, leading to issues like light leakage and reduced image clarity.
Innovation Solution
A liquid crystal composition with a larger vertical dielectric constant (ε⊥) and a larger ratio of ε⊥ to absolute dielectric anisotropy (ε⊥/|Δε|), along with a higher average elastic constant (Kave) is developed, comprising specific compounds such as those of general formulas I, II, and M, to enhance transmittance and contrast while maintaining appropriate optical anisotropy and clearing point.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If the dielectric anisotropy (Δε) is decreased to improve transmittance, then the transmittance increases, but the contrast ratio deteriorates
Solution Approach 1:
The patent changes the parameter of vertical dielectric constant (ε⊥) by introducing compounds with specific molecular structures (formulae I and II) that have large perpendicular dipole moments. This structural modification increases ε⊥, which improves transmittance through the IPS mode while maintaining appropriate contrast ratio by carefully controlling the dielectric anisotropy within the range of -3 to -8.
Solution Approach 2:
The patent creates a composite liquid crystal composition by combining compounds of formula I (with large perpendicular dipole moments and high ε⊥) and compounds of formula II (with specific elastic properties) in defined weight ratios (20-80 wt% and 80-20 wt% respectively). This composite approach allows simultaneous optimization of transmittance and contrast ratio that cannot be achieved with single compounds.
2Manufacturing precision
If the adjustment range of dielectric anisotropy and optical anisotropy is expanded to improve contrast, then the contrast ratio improves, but the device complexity increases
Solution Approach 1:
The patent achieves improved contrast ratio by controlling specific parameters within defined ranges: dielectric anisotropy Δε = -3 to -8, optical anisotropy Δn = 0.08 to 0.15, and vertical dielectric constant ε⊥ = 5 to 15. These parameter specifications provide a systematic approach to optimizing contrast without requiring complex device structures.
3Illumination intensity
If the vertical dielectric constant (ε⊥) is increased to improve transmittance in IPS mode, then the transmittance increases, but the response time may deteriorate
Solution Approach 1:
The patent increases ε⊥ to 5-15 (preferably 7-12) to improve IPS mode transmittance while maintaining fast response time by carefully controlling the average elastic constant Kave within 10-20 pN (preferably 12-18 pN). The specific molecular structures in formulae I and II are designed to achieve this parameter balance.
Solution Approach 2:
The composite composition combines compounds with high ε⊥ (formula I) and compounds with optimized elastic properties (formula II) to achieve simultaneous improvement in transmittance and response time. The synergistic effect of the composite allows ε⊥ = 7-12 and Kave = 12-18 pN to be achieved together, resolving the trade-off between transmittance and response speed.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The liquid crystal composition improves contrast and transmittance, resulting in better image clarity and faster response speed, while maintaining suitable operating temperature and threshold voltage, thus enhancing the performance of liquid crystal display devices.
Implementation Method 1
the impact of contrast on the visual effect is very critical... the larger the contrast is, the clearer and more eye-catching the image will be... In order to improve the transmittance of the liquid crystal medium, Δε of liquid crystal medium can be decreased
Implementation Method 2
the liquid crystal molecules will tilt towards the Z axis under the action of the vertical component of the edge electric field, resulting in the change of its optical anisotropy... it can be seen that effective Δn*d will affect Tr
Data Source
AI summary
The present invention provides a liquid crystal composition and a liquid crystal display device thereof. The liquid crystal composition comprises at least one compound of general formula I and at least one compound of general formula II. The liquid crystal composition has a larger vertical dielectric constant (ε⊥), a larger ratio of the vertical dielectric constant to the absolute value of dielectric anisotropy (ε⊥/|Δε|), a larger Kave value and a higher transmittance while maintaining an appropriate clearing point, an appropriate optical anisotropy, and an appropriate absolute value of the dielectric anisotropy, such that the liquid crystal display device comprising the same has a better contrast, a faster response speed and a better transmittance while maintaining an appropriate range of operating temperature and an appropriate threshold voltage.